JP2008022207A - Image processing apparatus and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processing apparatus from which an output closer to a more desirably simulated output result can be obtained in the case of outputting a result of applying color correction to image data including an image drawing instruction of an object subjected to prescribed overlapping designation. <P>SOLUTION: The image processing apparatus acquires the image data including the image drawing instruction of the object subjected to color designation, generates a raster image on the basis of the acquired image data, and selectively applies prescribed color correction to pixels representing an object subjected to color designation in a prescribed color space among pixels in the raster image. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image processing apparatus and a program.

  For example, in a general DTP (DeskTop Publishing) application, image data including an object drawing instruction is generated. For this object, color designation is made in any color space, and the drawing color of the object when the image data is printed by a printing machine or the like is determined based on the color designation (for example, patent) Reference 1).

Before the image data generated by such a DTP application is printed by a printing machine, there is a case in which an image is formed on a sheet by an image forming apparatus close to the user and the output result is confirmed. In this case, a predetermined color correction may be performed by the image forming apparatus at hand of the user in order to simulate the hue when it is finally output by the printing press. By instructing the image forming apparatus to form an image based on the correction value obtained by performing such color correction, the image forming apparatus can predict the output result of the printing press based on the original color designation, An image can be formed. As a result, the user can confirm the output result of the printing press with the image forming apparatus at hand before printing by the printing press. For example, such color correction is performed on each pixel included in the raster image after a raster image is generated based on an object drawing instruction.
JP 2004-174964 A

  In image data including such an object drawing instruction, colors may be designated in different color spaces for a plurality of objects included in one image data. For example, CMYK color space composed of four color components of cyan (C), magenta (M), yellow (Y), and black (K), and three colors of red (R), green (G), and blue (B). An RGB color space composed of color components. Here, when the color space used in the raster image generated by the image processing apparatus is, for example, the CMYK color space, it is necessary to convert the color of the object designated by the RGB color space to a color in the CMYK color space. There is.

  However, in such a case, if the color correction is performed on each pixel included in the raster image as described above, the color conversion is performed many times, and the amount of deviation from the color specified for the original object is increased accordingly. There is a possibility that. If it does so, it will become impossible to reproduce the output result by a printing machine accurately by color correction.

  The present invention has been made in view of the above circumstances, and one of its purposes is an output to be simulated when outputting a result of color correction performed on image data including an object drawing instruction. An object of the present invention is to provide an image processing apparatus and program capable of obtaining an output close to the result.

  In order to solve the above problems, an image processing apparatus according to the present invention includes an image data acquisition unit that acquires image data including a drawing instruction for an object for which a color is specified, and a raster image based on the acquired image data. A raster image generating means for generating, and a color correcting means for selectively performing a predetermined color correction on a pixel representing an object whose color is designated by a predetermined color space among the pixels in the raster image. , Including.

  In the image processing apparatus, the predetermined color space may be a color space used for a raster image generated by the raster image generation unit.

  The image processing apparatus further includes position information generating means for generating position information indicating a position of a pixel representing an object for which a color is designated based on the predetermined color space in the raster image, The correcting unit may selectively perform the color correction based on the generated position information.

  In the image processing apparatus, the raster image generation unit generates a first raster image based on an object that is color-designated by the predetermined color space among objects included in the acquired image data. A second raster image different from the first raster image is generated based on an object for which a color is specified by a color space other than the predetermined color space, and the color correction unit includes each color included in the first raster image. The color correction may be selectively performed by performing color correction on a pixel and combining the first raster image and the second raster image that have been subjected to color correction.

  Further, the raster image generation means, when an object for which color designation is made by the predetermined color space and an object for which color designation is made by a color space other than the predetermined color space overlap, Of these, the first or second raster image may be generated so that the pixel value of the pixel in the region where the objects overlap in the raster image based on the object arranged on the rear surface becomes zero.

  Further, the program according to the present invention includes an image data acquisition unit that acquires image data including a drawing instruction of an object for which a color is specified, a raster image generation unit that generates a raster image based on the acquired image data, and A computer is caused to function as color correction means for selectively performing predetermined color correction on a pixel representing an object whose color is designated by a predetermined color space among the pixels in the raster image. And

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. An image processing apparatus 1 according to an embodiment of the present invention is a print server, for example, and includes a control unit 11, a storage unit 12, and a communication unit 13, as shown in FIG. Yes. Here, it is assumed that the image processing apparatus 1 is connected to the user terminal 2 and the image forming apparatus 3 via a communication network.

  The control unit 11 is a CPU or the like, and operates according to a program stored in the storage unit 12. In the present embodiment, the control unit 11 generates and outputs raster image data for image forming processing by the image forming apparatus 3 based on the image data transmitted from the user terminal 2 via the communication network. To do. An example of processing executed by the control unit 11 in the present embodiment will be described later.

  The storage unit 12 is a computer-readable information storage medium that holds a program executed by the control unit 11, and includes at least one of a memory element such as a RAM and a ROM, a disk device, and the like. . The storage unit 12 also operates as a work memory for the control unit 11.

  The communication unit 13 is a network interface, and transmits information via the communication network in accordance with an instruction from the control unit 11. The communication unit 13 receives information that arrives via the communication network and outputs the information to the control unit 11.

  The user terminal 2 is an information processing apparatus used by a user such as a personal computer. In the present embodiment, the user terminal 2 executes a DTP application program, and finally generates image data to be printed by the printing press based on a user operation instruction.

  The image forming apparatus 3 forms the instructed image on the sheet based on the image forming instruction transmitted from the image processing apparatus 1. Here, the image forming apparatus 3 is based on designation of component values for each of the four color components of cyan (C), magenta (M), yellow (Y), and black (K) included in the image formation instruction. Assume that four color materials (toner or the like) are attached to a sheet to form an image.

  In the image processing system including the image processing apparatus 1 according to the present embodiment, a user who created image data for printing in the user terminal 2 simulated a printing result by an image forming apparatus (printing machine) to be simulated. It is used for confirming an image formed in the image forming apparatus 3 in advance. In the present embodiment, the image data created by the user terminal 2 is once transmitted to the image processing apparatus 1 in response to a user operation instruction. Then, the image processing apparatus 1 converts the image data into raster image data that can be processed by the image forming apparatus 3. Here, the image processing apparatus 1 corrects the drawing color included in the image data so that the image formed on the paper by the image forming apparatus 3 can reproduce the color tone of the image obtained as a result of printing by the printing press. Perform color correction processing. By this color correction processing, the difference in color reproduction characteristics between the image forming apparatus 3 and the printing machine to be simulated is absorbed, and the color of the image when printed by the printing machine by the image forming apparatus 3 is simulated. Can do.

  As shown in FIG. 2, the image processing apparatus 1 functionally includes an image data acquisition unit 21, a raster image generation unit 22, and a color correction unit 23. These functions can be realized by the control unit 11 executing a program stored in the storage unit 12. This program may be provided via a communication network such as the Internet, or provided by being stored in various information storage media readable by a computer such as a CD-ROM or DVD-ROM. It may be a thing.

  The image data acquisition unit 21 receives image data to be formed by the image forming apparatus 3 by receiving data transmitted from the user terminal 2. Here, the image data includes a drawing instruction for at least one object. This object is a variety of drawing elements constituting an image to be formed, and is a unit for color designation by the user.

  Here, the color designation of the object includes designation of a color space and designation of component values of each color component in the color space. Specifically, for example, when a color is specified for a certain object in the CMYK color space, a component value is specified for each color component of CMYK. Hereinafter, the color space used for specifying the color of the object is referred to as a user-specified color space. Note that the user-specified color space may be different for each object included in the image data.

  The raster image generation unit 22 generates a raster image based on the image data acquired by the image data acquisition unit 21. Hereinafter, the color space used for the raster image generated by the raster image generation unit 22 is referred to as an output color space. That is, the color of each pixel included in the generated raster image is represented by the component value of each color component in the output color space. The output color space is a color space used for image forming processing in the image forming apparatus 3 that performs image formation, and is a CMYK color space represented by four color components of CMYK here. Thereby, the image forming apparatus 3 can form an image based on a raster image including pixels of a color represented by the output color space generated by the raster image generating unit 22.

  Note that the raster image generation unit 22 generates a raster image for objects included in the image data acquired by the image data acquisition unit 21 for objects whose user-specified color space is different from the output color space. Then, color conversion processing for converting the color specified by the user-specified color space into a color by the output color space is performed. In this case, the raster image generation unit 22 converts the color specified by the user-specified color space into a color that can reproduce the output result from the image forming apparatus to be simulated. For example, when a color designation is made for an object in the RGB color space, the raster image generation unit 22 converts the designated color into a color in the CMYK color space, and uses the converted color for the CMYK color. Generate a raster image in space.

  The raster image generation unit 22 may generate position information together with the raster image in order to realize selective color correction by a color correction unit 23 described later. Alternatively, a plurality of raster images may be generated based on one image data acquired by the image data acquisition unit 21. These processes will be described later.

  The color correction unit 23 selectively selects a pixel representing an object whose color is designated by a predetermined color space (correction color space) among the pixels in the raster image generated by the raster image generation unit 22. Perform predetermined color correction. Here, the correction color space is assumed to be an output color space that is a color space used for a raster image generated by the raster image generation unit 22.

  Here, the color correction is designated for each pixel in the raster image so that the color of the image formed by the image forming apparatus 3 can reproduce the color formed by the image forming apparatus to be simulated. This is processing for determining a corrected component value (correction value) of each color component based on the component value of each color component in the output color space. This color correction process is realized by, for example, converting the component value of the color component designated for each pixel into a correction value according to a correction table stored in advance in the storage unit 12. By outputting the corrected raster image obtained by the color correction process to the image forming apparatus 3, the image forming apparatus 3 can form an image simulating the output result of the image forming apparatus to be simulated. .

  Next, some examples of processing in which the color correction unit 23 realizes selective color correction in cooperation with the raster image generation unit 22 will be described in detail.

  First, as an example of the first processing, an example in which the raster image generation unit 22 generates position information together with the raster image and the color correction unit 23 implements selective color correction using the position information will be described.

  In this example, the raster image generation unit 22 generates a raster image and also generates position information indicating the position in the raster image of a pixel representing an object for which a color is specified based on the correction color space. For example, the position information is data in which each pixel in the raster image is associated with a value (color space value) indicating a user-specified color space for the object represented by each pixel. In this case, the color space value may be binary data indicating whether or not the color designation based on the correction color space has been made, or may be a predetermined identification number for identifying each of a plurality of types of color spaces. Good. The position information is data including the color space value instead of the pixel value in the same data format as the image data of each plate indicating the pixel value (component value of the color component) of each pixel for each color component. Also good. In this case, the raster image generation unit 22 can generate position information as, for example, image data of a special color plane.

  Subsequently, the color correction unit 23 determines whether or not color correction is necessary for each pixel included in the raster image based on the position information generated by the raster image generation unit 22. For example, when position information including the color space value described above is generated, the color correction unit 23 performs color correction of each pixel depending on whether or not the color space value of each pixel included in the position information matches a predetermined value. Determine whether it is necessary. Then, color correction is performed for pixels determined to require color correction, and execution of color correction is limited for pixels determined to not require color correction.

  Here, an example of the flow of processing executed by the image processing apparatus 1 in the case of the first processing example will be described based on the flowchart of FIG.

  First, the image data acquisition unit 21 acquires image data including an object drawing instruction based on data transmitted from the user terminal 2 (S1). Next, the raster image generation unit 22 rewrites the drawing instruction for expanding the position information as the special color plane image data with respect to the drawing instruction included in the acquired image data (S2).

As a specific example, when the acquired image data is described in the PostScript language, the raster image generation unit 22 first adds a designation to output a special color plane. Then, following a drawing instruction for an object for which a color is specified in a color space other than the correction color space, for example, a drawing instruction as exemplified below is added.
gsave% Save graphics state (assuming A)
true setoverprint% Set to overprint
[/ Separation (TAG) / DeviceGray {}] setcolorspace% Set to spot color
1 setcolor% Set color space value
0 0 1 1 rectfill% Fill the image drawing area
grestore1 Restore graphic state other than% coordinate position (return to A)

  In the above example, the part below% in each line is a comment part indicating the contents of processing of each line. “TAG” indicates special color image data representing position information. The overprint setting is made to prevent the pixel values set for the other CMYK color components from being invalidated by the pixel value setting for the special color plate. Accordingly, the color of the original image data can be represented by the image data of each plate of CMYK, and the information of the color space designated for the object can be represented by the image data of the special color plate.

  Subsequently, the raster image generating unit 22 generates a raster image based on the image data in which the drawing instruction has been rewritten in S2 (S3). By this processing, as shown in FIG. 4, the raster image generation unit 22 performs image data of each plate of CMYK, image data of a special color plate representing position information including color space values indicating the color space of each pixel, Is generated. In the above-described rewriting example, the image data of the special color plane has a maximum value for the pixel where the object for which the color is specified by a color space other than the correction color space is located, and 0 for the other pixels. It becomes the data that has.

  Next, the color correcting unit 23 applies the target pixel in the raster image generated in S3 based on the pixel value (color space value) of the target pixel included in the special color plane image data (position information). Then, it is determined whether or not to perform color correction (S4). In the above example, it is determined that color correction is performed when the pixel value of the target pixel is the maximum value. If it is determined that color correction is to be performed, a predetermined color correction process is performed on the target pixel (S5). The color correction unit 23 repeats the processes of S4 and S5 for all the pixels in the raster image. Thereby, selective color correction is performed on the raster image.

  Thereafter, the color correction unit 23 instructs the image forming apparatus 3 to form an image based on the raster image that has been subjected to the selective color correction by the processing up to S5 (S6). As a result, the color-corrected raster image is formed on the paper by the image forming apparatus 3.

  Next, as an example of the second process, the raster image generation unit 22 generates a plurality of raster images, and the color correction unit 23 performs color correction on pixels included in some of the raster images. An example will be described.

  In the second processing example, the raster image generation unit 22 performs the first rasterization based on the objects that are color-designated by the correction color space among the objects included in the image data acquired by the image data acquisition unit 21. An image is generated, and a second raster image different from the first raster image is generated based on an object for which a color is specified by a color space other than the correction color space.

  In this case, the raster image generation unit 22 performs the following process when an object for which the color is specified by the correction color space and an object for which the color is specified by a color space other than the correction color space overlap. It is also possible to determine the pixel value of a pixel in a region where the objects overlap (overlapping region). That is, among these objects, the pixel value of the pixel in the overlapping area in the raster image generated based on the object arranged on the rear surface is set to 0. For example, when the user-specified color space of the object arranged on the rear surface is the correction color space, the pixel value of the pixel in the overlapping region in the first raster image is set to 0. Conversely, when the user-specified color space of the object arranged on the rear surface is a color space other than the correction color space, the pixel value of the pixel in the overlapping area in the second raster image is set to 0.

  Here, when an object is arranged on the rear surface, when it overlaps with another object, it means a state in which the object cannot be seen on the finally generated raster image, hidden behind the other object. . Whether an object is arranged on the rear surface or the front surface is determined by, for example, the drawing order of the objects. That is, among the objects that overlap each other, the object to be drawn last is arranged on the front surface, and the other objects are arranged on the rear surface. In this way, by setting the pixel value of the pixel in the overlapping region to 0 for either the first or second raster image, the color is set for both the first and second raster images for one pixel. Can be prevented. As a result, when the first and second raster images are combined later, it can be prevented that it becomes impossible to determine which color should be given priority.

  Subsequently, the color correction unit 23 performs a color correction process on each pixel included in the first raster image generated based on the object whose color is specified by the correction color space. On the other hand, the execution of the color correction process is restricted for the second raster image generated based on the object for which the color is specified by other than the correction color space. Then, the first raster image subjected to color correction and the second raster image not subjected to color correction are synthesized. That is, the color correction unit 23 superimposes the first and second raster images, and obtains a raster image in which the color component of each pixel is determined based on the pixel value of the pixel at the same position included in the two raster images. Generate. Thereby, a raster image on which the color correction processing has been selectively executed is obtained.

  Here, an example of the flow of processing executed by the image processing apparatus 1 in the case of the second processing example will be described based on the flowchart of FIG.

  First, as in the case of the first processing example, the image data acquisition unit 21 acquires image data including an object drawing instruction based on data transmitted from the user terminal 2 (S11). Next, the raster image generation unit 22 rewrites the drawing instructions for generating the first and second raster images with respect to the drawing instructions included in the acquired image data (S12).

As a specific example, when the acquired image data is described in the PostScript language, the raster image generation unit 22 first adds a designation to output a special color plane as in the first processing example. However, the special color plates in this example are prepared as many as the number of color components in the output color space (here, four of CMYK), and are used to generate the first raster image. Further, the raster image generation unit 22 rewrites the drawing instruction as exemplified below. For example, it is assumed that the image data acquired in S <b> 11 includes a drawing instruction for an object for which color designation is performed using the following correction color space.
newpath% clear shape
0 0 moveto move to% (0,0)
1 0 lineto% Create a straight line from (0,0) to (1,0)
1 1 lineto% Create a straight line from (1,0) to (1,1)
0 1 lineto% Create a straight line from (1,1) to (0,1)
0 0 0 1 setcmykcolor% Specifies the color to be drawn (black)
fill% fill the constructed shape

In this case, the raster image generation unit 22 rewrites the drawing instruction as exemplified below.
newpath% clear shape
0 0 moveto move to% (0,0)
1 0 lineto% Create a straight line from (0,0) to (1,0)
1 1 lineto% Create a straight line from (1,0) to (1,1)
0 1 lineto% Create a straight line from (1,1) to (0,1)
0 0 0 1 setcmykcolor% Specifies the color to be drawn (black)
gsave% Save graphics state (assuming A)
gsave% Save graphics state (assuming B)
fill% fill the constructed shape
grestore% Restore graphic state (return to B)
true setoverprint% Set to overprint
[/ DeviceN [(C1) (M1) (Y1) (K1) / DeviceCMYK {}] setcolorspace% Set to another CMYK version
currentcolor setcolor% Set the specified color for the object
fill% Fills the spot color with a figure
grestore1 Restore graphic state other than% coordinate position (return to A)

  In the above example, the part below% in each line is a comment part indicating the content of the process in each line as in the first process example. “C1”, “M1”, “Y1”, and “K1” indicate the special color plates corresponding to the respective color components of the first raster image, and the raster image generation unit 22 converts the first raster image into these special color plates. It generates as image data.

  Subsequently, the raster image generating unit 22 generates a raster image based on the image data for which the drawing instruction has been rewritten in S12 (S13). As a result of this processing, the raster image generation unit 22, as shown in FIG. 6, includes a first raster image represented as four spot color plane image data and a second raster image represented as CMYK plane image data. And generate.

  Next, the color correction unit 23 performs a predetermined color correction process on each pixel in the first raster image among the raster images generated in S13 (S14). Then, the first raster image subjected to color correction obtained in S14 and the second raster image generated in S13 are combined (S15).

  Thereafter, the color correction unit 23 instructs the image forming apparatus 3 to form an image based on the raster image obtained by the synthesis in S15 (S16). As a result, the color-corrected raster image is formed on the paper by the image forming apparatus 3.

  According to the present embodiment described above, the color designation by the correction color space is performed by selectively performing predetermined color correction on the pixel representing the object for which the color is designated by the correction color space. In addition to performing color correction for pixels, overlapping color correction can be limited for pixels that have undergone color conversion to other correction color spaces, and an output closer to the output result that you want to simulate can be obtained. Can do.

1 is a block diagram illustrating a schematic configuration of an image processing apparatus according to an embodiment of the present invention. It is a functional block diagram showing the function of the image processing apparatus which concerns on embodiment of this invention. It is a flowchart which shows an example of the process performed by the image processing apparatus which concerns on embodiment of this invention. It is explanatory drawing which shows an example of the raster image produced | generated by the image processing apparatus which concerns on embodiment of this invention, and position information. It is a flowchart which shows another example of the process performed by the image processing apparatus which concerns on embodiment of this invention. It is explanatory drawing which shows another example of the raster image produced | generated by the image processing apparatus which concerns on embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Image processing apparatus, 2 User terminal, 3 Image forming apparatus, 11 Control part, 12 Storage part, 13 Communication part, 21 Image data acquisition part, 22 Raster image generation part, 23 Color correction part

Claims (6)

Image data acquisition means for acquiring image data including a drawing instruction of an object for which a color is specified;
Raster image generating means for generating a raster image based on the acquired image data;
Color correction means for selectively performing a predetermined color correction on a pixel representing an object whose color is designated by a predetermined color space among the pixels in the raster image;
An image processing apparatus comprising: The image processing apparatus according to claim 1.
The image processing apparatus, wherein the predetermined color space is a color space used for a raster image generated by the raster image generation unit. The image processing apparatus according to claim 1 or 2,
In the raster image, further comprising position information generating means for generating position information indicating the position of a pixel representing an object for which color designation based on the predetermined color space is made,
The image processing apparatus, wherein the color correction unit selectively performs the color correction based on the generated position information. The image processing apparatus according to claim 1 or 2,
The raster image generating means generates a first raster image based on an object that is color-designated by the predetermined color space among the objects included in the acquired image data, and a color other than the predetermined color space Generating a second raster image different from the first raster image based on an object for which color is designated by a space;
The color correction unit performs the color correction on each pixel included in the first raster image, and selectively combines the first raster image and the second raster image that have been color corrected. And performing the color correction. The image processing apparatus according to claim 4.
The raster image generating means may include a rear surface of each object when an object for which color is designated by the predetermined color space and an object for which color is designated by a color space other than the predetermined color space overlap. An image processing apparatus, wherein the first or second raster image is generated so that a pixel value of a pixel in a region where each object overlaps in a raster image based on an object arranged on the object. Image data acquisition means for acquiring image data including a drawing instruction of an object for which a color is specified;
Raster image generation means for generating a raster image based on the acquired image data, and a pixel selected from among the pixels in the raster image that represents an object for which a color is designated by a predetermined color space Color correction means for performing predetermined color correction automatically,
A program characterized by causing a computer to function.

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